1. Field of the Invention
This invention relates to chip-type semiconductor light-emitting devices and, more particularly, to a chip-type semiconductor light-emitting device having a semiconductor light-emitting chip connected to an electrode on a substrate and molded together with part of the electrode.
2. Description of the Prior Art
A conventional chip-type semiconductor light-emitting device of this kind is shown in FIG. 4. This chip-type semiconductor light-emitting device 1 includes a substrate 2. At opposite ends of the substrate 2, a pair of electrodes 3 and 4 are formed. The electrodes 3 and 4 include respective terminals 3a and 4a. Each of the terminals 3a and 4a is formed, at its width center, with a protrusion 3b, 4b. Also, a pad 4c is formed at a tip of one protrusion 4b. The electrodes 3 and 4 are structured by three layers, i.e. a Cu (copper) layer, an Ni (nickel) layer and an Au (gold) layer, as shown in FIG. 4(B). The formation of an Au layer, as an uppermost layer, improves the adhesion with solder and electrical connection to a metal wire 5.
The semiconductor light-emitting chip (hereinafter referred merely to as “LED chip”) 6 is bonded on the pad 4c in the electrode 4. The LED chip 6 at a back electrode is electrically connected with the electrode 4. Wire bonding is made using the metal wire 5 between a surface electrode 6a on the LED chip 6 and the protrusion 3b in the electrode 3. Furthermore, the protrusion 3b, the protrusion 4b, the pad 4c, the metal wire 5, the LED chip 6, etc. are encapsulated by a translucent synthetic resin mold 7. Such chip-type semiconductor light-emitting device 1 is to be mounted in a state that the backside of the substrate 2 is in contact with a surface of a circuit board. In the reflow process, electrical connection is provided through solder 8 between the terminals 3a and 4a and the wiring pattern on the circuit board.
In the prior art, there is a fear that, when repeatedly conducting a reflow process, solder melt 8 possibly intrudes into the mold 7 via the protrusions 3b and 4b, possibly reaching the metal wire 5 or the LED chip 6. If the solder 8 reaches the metal wire 5 or the LED chip 6, they might be stripped off or damaged due to the impact caused upon such reach of solder, resulting in erroneous operation of the chip-type semiconductor light-emitting device 1.